# New Ultralight and LSA Trainer design PAIR

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Rienk, Aug 1, 2010.

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## What is your interest/input in such a project?

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1. Aug 3, 2010

### Inverted Vantage

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But it was reiterated several times that this aircraft should not be designed for cruise or long climbs. As for the engine, yea, pretty neat looking - how about production amount? Is there enough of them around/being made or is it just the prototype?

2. Aug 3, 2010

### Rienk

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I'm also very interested in electric.
I'm in discussions with a company that makes a racing rotary engine; if it's derated, I think that it would be a good option - though expensive. It supposedly weighs 35lbs putting out 48hp - for 100 hours of racing before rebuild.
If it was derated to 30-35 hp, it would probably last 500+ hours in an ultralight, even with aerobatics.

I also see that one of the PPC outfits uses the Generac with a standard five gallon tank of Propane! Safe, 110 octane, doesn't really go bad... the only issue may be the weight of the tank - but talk about easy and safe fuel change!

Interesting options...

3. Aug 3, 2010

### Rienk

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Remember what you all put on the poll (check the stats again, if you forget).
Most of you would be interested in buying this airplane if it met the price point - and most of you put that at below $10k. How do you envision a production aircraft (that needs at least 40% for GA and profit) if the engine costs$4-6K?

You guys are chasing a pipe dream... trying to have your cake and eat it too. Is it possible if it were simply a group project at just "cost"? Probably...

But this thread is about getting the masses interested in aviation by introducing an aircraft that they can afford.

Let's get our heads out of the clouds and get back to the task at hand.

Industrial gasoline engine for now - electric and others for later iterations.

4. Aug 3, 2010

### Rienk

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HERDING CATS :grin:

(But I'm willing to do it, even if many drop out, since I intend to see this project through to completion)

5. Aug 3, 2010

### Inverted Vantage

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$20,000 is the price to beat. At that range you can set up monthly payments below$400, which is reasonable for most people with a decent interest in the sport.

6. Aug 3, 2010

### Autodidact

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I personally think, that for mass consumption, electric wins hands down because of the low (nonexistent?) maintenance, and the very low operating costs. It's the least amount of bother to just get in and go fly. But, it's new technology, and as such is prone to implementation related problems (supply, know how, etc.).

But I would suggest that the plane be designed with provision to be powered by either electric or IC. This can be done since some of the electric planes now flying have been so readily converted from gas powered planes. You still have an engine (or motor), and you still have a fuel supply.

As far as IC engines, I think the opposed twin is the best. I think the way to get the engine is to make new parts (crankshaft, crankcase, heads, etc.,...) based on an already proven conversion like the 1/3 corvair or the 1/2 VW. That way, you wouldn't have to design a new engine; you're just making parts with a slightly different outer shape to an already proven design. With CNC tech, this would not be hard to do and some extra revenue could be generated by sales of the engine by itself to other people who will take the more difficult but less expensive route of plans building any of several different designs already in existence. Since the plane is being designed around the Generac, the opposed twin would work just as well.

Last edited: Aug 3, 2010
7. Aug 3, 2010

### KeithO

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Rienk, you are killing me.... First no 2 strokes, then no purpose built fully assembled 4 stroke engines for $5k... Have you priced out a great plains VW yet ? An engine based on mass production parts that has run in production for over 40 years and all tooling and engineering has long since been amortized ? Lets see:VW Long Block Kits by Great Plains Aircraft Supply Co., Inc. Long block 1600cc 50hp$2830
Accessory package #8 (hand prop,distributor, alternator, prop hub intake manifold, engine X mount) $1045.50 So, still no carb yet... Or, take the flywheel drive engine: Whole package with alternator, hand prop no carb for a mere$4361.90
Bosch 009 Distributor for VW Engines by Great Plains Aircraft Supply Co., Inc.
Thats for the 1835cc "basic" package.

Add $363 for a Zenith carb. Add$950 for assembly.

Gee it is adding up pretty fast ! No wonder then that when one starts with an industrial engine that most people have to buy complete for $1700, tear it down, blueprint it, modify the castings to remove excess weight, add the prop hub, replace the carb and exhaust, one arrives at a figure like Valley Engineerings$4995. And it will never be worth what a Verner will be, nor will it last anywhere near as long.

The prices from the people mentioned including Valley Eng, Great Plains, Verner etc are all from people who have been in business for a while. Typically they are all modest outfits, no flashy offices or corporate jets etc, so I am not sure their margins are very "fat".

Sorry to say, but shooting for a 10k delivered price is only going to get you and your investors broke. Something else to consider is that you had better appeal to the pilot wannabees, since Joe public who is competing for the Darwin prize is going to sue you back to the stone ages after you have sold enough of them.

8. Aug 4, 2010

### Inverted Vantage

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I think he was saying that you COULDN'T shoot for a 10k delivery price, Keith

9. Aug 4, 2010

### KeithO

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As far as I know, the continuous power is at least equivalent to a 1/2VW and with the included reduction drive it will swing a bigger prop for more thrust and 20-40lb less weight.

10. Aug 4, 2010

### gyrojeff

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hi, I'm new to the forum but how about wood and foam construction like the skypup uses. The whole airframe on this bird can be built for around $2000 minus engine. The dow blue foam can be purchased from lowes. The design easily meets part 103 specs usually coming in anywhere from 200 to around 240 pounds on the high side The 2 axis control system might be a turn off for some but its very effective, just throwing some ideas out there. theres a pretty active discussion on the design here. Skypup-club : Skypup-club #### Attached Files: • ###### pup1.jpg File size: 29.6 KB Views: 1,331 • ###### pup2.jpg File size: 22.9 KB Views: 1,595 11. Aug 4, 2010 ### Dana ### Dana #### Super ModeratorStaff Member Joined: Apr 4, 2007 Messages: 8,679 Likes Received: 3,056 Location: CT, USA Yes, but if you're designing an airplane for the masses you don't want the pilot to have to remember engine operating limitations like that. And you may not design for cruise, but the first thing a new pilot (even of an ultralight) wants to do is go somewhere. Check out the battery charge times, and then decide if it's "the least amount of bother to just get in and fly." Even if the battery can handle a rapid charge, can you find an airport with the required amperage electric service to do it? And what if you land away from home? Don't get me wrong, I love the idea of an electric airplane... but even though quite a few have flown, the battery technology just isn't here (or even on the horizon) yet. Nor is it affordable. Batteries for a practical electric plane will run around$10K. Even the hybrid cars don't make sense if you compare the battery service life and replacement cost to the cost of fuel saved.

-Dana

Aviation is like drugs: You go up, then you come down. You are out a big pile of money and have nothing to show for it but the experience.
And you can't wait to do it again.

12. Aug 4, 2010

### Hot Wings

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Eventually electric will be the power of choice for some planes but right now, for an LSA, it's a non-starter. ASTM is still working on consensus standards for electric planes and from my take are still a ways from getting the job completed.

We can't design to standards that don't yet exist.

13. Aug 4, 2010

### KeithO

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Dana, it sounds like our UL is going to need a very simple ECU.
Even an 8 bit controller will be sufficiently intelligent to be able to save the engine from the nut behind the wheel. If the Pilot does not back off the power more than a certain amount after takeoff, (one can integrate time vs manifold pressure) then one retards the timing a certain amount and it will accomplish a similar power reduction. The fuel efficiency may not be equal, but one can prevent damage to the engine.

Automotive Small Engine Control Solutions By Freescale

Right here is an evaluation board all built up with source code: KIT33812EKEVBE Product Summary Page

Actually, this is a complete system with CPU. The system above is just the interface to the various on engine devices..
http://www.freescale.com/webapp/sps...rentCode=MC33812&fpsp=1&nodeId=01435979968460

Last edited: Aug 4, 2010
14. Aug 4, 2010

### Autodidact

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That can be at least partially corrected by having a conformal battery pack that can be changed quickly, but all of the other objections raised (including the price of batteries) sound pretty valid to me, I'm not trying to push it much.

15. Aug 4, 2010

### Rienk

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Here is another engine to consider.
If anyone has the inclination (and connections) it would be interesting to see if any of these industrial engines share internals with their motorcycle cousins.

Performance valves, pistons, cam, ECU, etc, would make for a cost effective and powerful engine... and not too heavy once you remove all the unnecessary stuff attached to it.

FX1000V-DFI 37.0HP
Kawasaki Engines and Power Products - Engines - FX1000V-DFI

FEATURES
90° V-twin
High performance lubrication system
Automatic compression release
Multi-port digital fuel injection
Electronic governor control
Compact electronic control unit
Choke-free operation
Electronic cold operation enrichment
Electronic altitude compensation
Low pressure fuel injection technology w/ electronic fuel pump
Cast-iron cylinder liners
Metal engine cover
SPECIFICATIONS
Engine Type Forced Air-Cooled V-twin 4-cycle Digital Fuel Injected, Vertical Shaft OHV Gasoline Engine
Number of Cylinders 2
Bore x Stroke 3.5 x 3.15 in. (89.15 x 80mm)
Displacement 999cc (61 cu. in.)
Compression Ratio 8.4:1
Maximum Power 37.0hp (27.6kW) / 3600 rpm
Maximum Torque 60.6 ft. lbs. (82.2 N•m) / 2400 rpm
Oil Capacity 1.8 U.S. qt. (1.7 liter) w/Filter
Dry Weight (without muffler) 138.0 lbs. (62.6kg)

PS - I would appreciate it if someone can tell me how to embed photos in these posts, other than as attachments (?)

Last edited: Aug 4, 2010
16. Aug 4, 2010

### Rienk

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As Jordan said, I'm not the one shooting for a $10k sales price - I'm just trying to get everyone to realize that it can't be done commercially for that price. Two things - a higher price point is required, and a low cost engine is necessary. Just like there is "weight creep" in most aircraft, this project is subject to "cost creep." For now, let's forget about selling thousands... even if we want to sell hundreds, there will be a certain magic price point that needs to be met (yet to be determined, let alone proven). It really is a simple matter of working backward from there, to see if a viable business plan AND aircraft can be formulated together. Don't forget, I'm already gearing up for production of a single seat sport plane, the base model of which will be using an industrial engine. To blueprint it, replace carbs, exhaust, valves, and oil cooler and add a prop hub (direct drive) will run about$2500 (my cost). This will give us a reliable 40-45 hp, but using a smaller prop (which will be fine if we end up going with a pusher/boom configuration).

Ironically, I can put together a 120hp, turbocharged, EFI engine and redrive package (around 140 lbs) for about $9k (my cost), which we will be using in both the Solo and Duet. Unfortunately, that is simply too heavy (and powerful) for a 103UL. The Kawasaki is worth exploring, especially if we can use OTS parts from motorcycles to get a reliable 50-60hp out of it (800-1000cc engines, and the motorcycles of that displacement easily get more than that - even derated for longevity or full duty cycle). To be able to sell this aircraft for$14,800 (a nice marketing number), we are going to have to be able to produce it for $8-9k. So let's do some math.$3,000 for firewall forward.
$1,000 for avionics and electronics.$1,500 for materials ($10/lb)$ 500 for miscellaneous hardware (nuts, bolts, rod ends, etc)
$2,000 for labor (500 hrs, at$4/hr - overseas)​

This does not include amortizing development cost, which would have to be sweat equity and/or contributed capital.

Those are our rough numbers.
Manufacturing and marketing company would be an IBC.

Last edited: Aug 4, 2010
17. Aug 4, 2010

### Dana

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OK, but you still need a way to allow the pilot to override the ECU if he gets into a situation where he needs full power right now when the ECU is saying he can't have it. Not unlike the "war emergency" power settings beyond the throttle gate in WWII fighter planes. Then what? Is the engine damaged? Does it need a teardown? What about warranty issues? Not saying it can't be done, just things to consider.

-Dana

Members of Congress should be compelled to wear uniforms like NASCAR drivers, so we could identify their corporate sponsors.

18. Aug 4, 2010

### Inverted Vantage

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Would a pod and boom really be that much cheaper than a standard full on fuselage? What sort of difference in construction time/simplicity are we looking at?

19. Aug 4, 2010

### Autodidact

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That's a good question - mainly I just like the way it looks! But, if you going to use metal structure with a fairing, pod and boom might make sense by reducing the size of the fairing needed as well as providing about a 1/3rd of the fuselage structure ( by length) ready made. The constant section makes some sense because it needs to withstand torsion as well as bending. But it would only be a cost saving measure; structurally it is slightly less efficient.

I'm thinking a CNC'd bulkhead that is also the seat-back, the boom attaches to that via a collar machined into the bulkhead an some short struts. The bulkhead is also the spar attachment or carry-through. The forward fuselage structure, either welded or rivetted tube OR sheet OR plate or whatever, also bolts to the main bulkhead. The wings? Umm...

20. Aug 4, 2010

### Rienk

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I don't know.
It really centers around whether we go tractor or pusher.
In a pusher design, we could use a single boom (ala Strojnik) or a double boom outside the prop.
I kind of like the double boom idea if it's a high wing; you can have a finished center section with removable outer wing panels, an inverted Vtail between the booms, with tailwheels on each.
If we went single boom, it seems to make sense to follow the pattern of Strojnik, exepct make a "cooler" cockpit pod. The wing in ground effect might be an issue, as would landing in rough fields (but gliders do that all the time, though they are set up for it).

If we go tractor, then a typical lattice work is the obvious choice.
if tubing is used, then the issue becomes whether to weld or rivet and gusset. If we were to choose gussets (for removal of parts, as Dana suggests), then I would suggest square tubing ladder fuselage (with formers for turtledeck). Miter cutting square tubing would be simple, as would alignment of gussets for attachment.

A wild thought just came to me... I wonder if there is some sort of tubing material that we could use PEX style connectors on? Talk about simple assembly!

Anyway, we really need to come to terms with tractor or pusher, and maybe sketch out some design ideas.
If everyone could draw and scan their ideal plane (for this mission), it would be great for everyone to look at the various concepts.